Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAPperformance for the analytical methods that will be used to support Phase 1 decommissioningdata collection activities.Sampling and analysis will proceed as follows:1. The reference area will be divided into ten 200-m 2 areas. Two sets of ten soil sampleswill be collected, with two samples from each 200-m 2 area. One set of samples will berepresentative of soils from the surface to a depth of 15 cm. The second set will berepresentative of soils from 15 cm to a depth of 1 m. Sufficient soil mass will be collectedto allow analysis of all 18 ROIs and the 12 potential ROIs. Each sample will be fieldhomogenized, containerized, and labeled in a manner that clearly identifies the area fromwhich it was taken and the depth profile it represents.2. The resulting 20 samples (10 samples representing a 15 cm surface soil depth and 10samples representing the 15 cm – 1 m surface soil depth) will be submitted for analysis ofall 18 ROI and the 12 radionuclides of potential interest.Four soil cores will be obtained from within the reference area to a depth of at least 1 m into theLavery Till. The locations of the soil cores will be selected so that they are representative of fourquadrants within the reference area. The soil cores will be retrieved in a manner that allowsretrieval of intact cores and down-hole gamma scans by using a suitable detector. Down-holegamma scans will be conducted by taking a 30-second static reading at 15-cm intervals downhole.Data will be recorded in electronic spreadsheets in a fashion that clearly identifies thedetector type and identifier, the location of the core, the depth of the reading, and gross counts incounts per minute. Soil cores will also be scanned ex situ with a suitable detector. As part of thiswork, the soil type will be recorded for the length of the soil core along with soil moistureestimates.8.3 Radionuclide-Specific Background Activity ConcentrationsIn many instances, the CSAP pre-remediation decision-making process described in the attachedappendices requires a determination of whether soil sample results are consistent withbackground conditions or not. The Phase 1 DP provides an analysis of background activityconcentrations for ROIs in Section 4.2.2 and Appendix B based on historical data for surface soilsRev. 1 62